Field of the Invention
The present invention relates to a process for preparing substituted phenylisoxazoline derivatives.
Description of Related Art
Substituted phenylisoxazoline derivatives are useful intermediates in the production of active agrochemical ingredients (see, for example, WO 2008/013925, WO 2009/094407, WO 2010/123791).
There are various known processes for preparing such substituted phenylisoxazoline derivatives.
WO 2011/085170 describes, for example, a process for preparing these phenylisoxazoline derivatives by [3+2] cycloaddition with a chloroxime with a styrene and downstream Grignard addition and halogenation (Scheme 1).

A disadvantage of this process is that the use of further functional groups which can react directly with a Grignard reagent is impossible.
WO 2011/085170 describes, for example, a process for preparing these phenylisoxazoline derivatives by [3+2] cycloaddition with a chloroxime with a styrene and downstream halogenation (Scheme 2).

Disadvantages of this process are the technically complex preparation of the chloroxime shown.
WO 2011/072207 describes a [3+2] cycloaddition proceeding from a styrene with a chloroxime containing the required haloketone (Scheme 3).

Disadvantages of this process are the technically difficult preparation of the chloroxime shown and the large excesses required.
WO 2008/013925 describes the reaction of dichloroacetone with tert-butyl nitrite and the subsequent [3+2] cycloaddition with a styrene (Scheme 4).

A disadvantage of this process is that dichloroacetone is not available in industrial volumes and the reaction with tert-butyl nitrite is demanding for safety reasons.
Because of the importance of substituted phenylisoxazoline derivatives as a unit for synthesis of novel active agrochemical ingredients, the problem addressed is that of finding a process which can be used on the industrial scale and inexpensively. It is also desirable to obtain the specific phenylisoxazoline derivatives with high yield and high purity, such that the target compound preferably does not have to be subjected to any further potentially complex purification.